Process for obtaining diethylbenzene

ABSTRACT

A PROCESS FOR OBTAINING DIETHYLBENZENE FROM ETHYLBENZENE WHICH RESULTS FROM THE CATALYTIC REFORMING OF GASOLINES. THE ETHYLBENZENE IS DISPROPORTIONATED IN THE PRESENCE OF A CATALYTIC COMPLEX BASED ON ALUMINUM CHLORIDE AND POLYALKYBENZENES IN THE AMOUNT OF 3-10% RELATIVE TO ETHYLBENZENE, AT A TEMPERATURE OF 80-100*C. IN THE ABSENCE OF HYDROGEN. THERE IS OBTAINED A MIXTUTE OF DIETHYLBENZENE, BENZENE, AND ETHYLBENZENE CONTAINING AT MOST 1.5% OF ORTHO-DIETHYLBENZENE AND AT MOST 2.9% OF POLYALKYLBENZENES.

TInited States Patent Office Patented Dec. 21, 1971 3,629,350 PROCESSFOR OBTAINING DIETHYLBENZENE Vladimir Mocearov, Bucharest, and GeorgetaOsomontanyi and Mihail Mihailescu, Ploesti, Rumania, assignors toMinisterul Industriel Chimice, Bucharest, Rurnania No Drawing.Continuation-impart of application Ser. No.

871,594, Nov. 6, 1969, which is a continuation of application Ser. No.633,713, Apr. 26, 1967. This application Sept. 8, 1970, Ser. No. 70,481Int. Cl. C07c 3/62 U.S. Cl. 260-672 T 6 Claims ABSTRACT OF THEDISCLOSURE A process for obtaining diethylbenzene from ethylbenzenewhich results from the catalytic reforming of gasolines. Theethylbenzene is disproportionated in the presence of a catalytic complexbased on aluminum chloride and polyalkylbenzenes in the amount of 310%relative :to ethylbenzene, at a temperature of 80100 C. in the absenceof hydrogen. There is obtained a mixture of diethylbenzene, benzene, andethylbenzene containing at most 1.5% of ortho-diethylbezene and at most2.9% of polyalkylbenzenes.

CROSS REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of application Ser. No. 871,594, filed Nov. 6,1969, and now abandoned which is in turn a streamlined continuation ofapplication Ser. No. 633,713, filed Apr. 26, 1967 and now abandoned.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates to a process for obtaining diethylbenzene from ethylbenzeneresulting from the catalytic reforming of gasoline.

Prior art In the prior art in this field, various processes forobtaining diethylbenzene are known among which can be mentioned aprocess for the alkylation of benzene with ethylene in the presence ofaluminum chloride or a process for alkylation of ethylbenzene withethylene. The first of the above mentioned processes presents thedisadvantage of obtaining low diethylbenzene output since the latter isobtained in the form of a secondary product of the process for obtainingethylbenzene together with other polyethylbenzenes. The second mentionedprocess overcomes the disadvantages of the first by obtainingdiethylbenzene as the main reaction product, its output beinghigh. Butboth processes have the disadvantage of their laborious technologyinvolving a step for obtaining ethylene by dehydration of ethyl alcoholor by pyrolysis of refinery gases followed by alkylation in the presenceof aluminum chloride and also involving locating the installation forproducing diethylbenzene near a source Of ethylene.

Also known is a process (US. Patent No. 2,739,993) for the conversion oftoluene to other aromatic hydrocarbons and to naphthenes whereintoluene, in the presence of a great excess of hydrogen is subjected, inthe liquid phase at a temperature of 50-300 C. to the action of 0.1 to10 moles of aluminum chloride per mole of toluene. Characteristic ofthis process is the fact that there is always obtained thereby one ormore compounds having a lesser number of carbon atoms than the startingtoluene.

SUMMARY OF THE INVENTION According to the present invention,ethylbenzene, together with 3l0%, preferably about 5% by weight of acatalyst which is AlCl are introduced to a reaction zone in the absenceof any hydrogen and reacted at a temperature of -100 C. at atmosphericpressure. The optimum results are obtained in about 5 minutes when thetemperature is C.

When compared with the process disclosed in US. Patent No. 2,739,993 itis seen that the present invention specifically excludes hydrogen whilethe known process specifically requires same. Additionally, in thepresent invention a much smaller amount of catalyst is used than in theknown process. In the known process, 0.1 to 10 moles of A1Cl3 are usedper mole of toluene. This is the equivalent of about 14.5l450%; While inthe present invention, only 3l0'% of A101 is used.

DETAILED DESCRIPTION The present invention overcomes the disadvantagesof the known processes in that diethylbenzene (as raw material forobtaining divinylbenzene) is obtained by disproportionation ofethylbenzene obtained from catalytic reforming in the presence of acatalytic complex based on aluminum chloride in the amount of 3-10%relative to ethylbenzene, preferably 5%, at a temperature of 80 100 C.in the absence of hydrogen which leads to a conversion of 33% by weightof ethylbenzene to diethylbenzene, the final yield being 70% by weightrelative to the ethylbenzene introduced into the reaction. Thediethylbenzene obtained by disproportionation contains a maximum of 1.5%of the ortho-isomer and thus this process is more advantageous than theabove mentioned process which yields a higher proportion ofo-diethylbenzene, and by dehydrogenation of the latter there is obtainednaphthalene.

An example of the application of the invention is presented as follows:1000 g. of ethylbenzene of 98% minimum purity obtained by catalyticreforming of gasolines and 50 g. of A101 are introduced into analkylation reactor constructed of Bakelited steel. The reactor is heatedto 100 C. and intimate contact between ethylbenzene and the catalyst isprovided by intensive stirring.

After about 5 minutes, an optimum diethylbenzene concentration in thereaction mass is established, this reaction mass consisting of: 22% byweight benzene, 41% by weight ethylbenzene, 33% by weightmeta-i-paradiethylbenzene, 1.5 by weight ortho-diethylbenzene, 2.5% byweight polyethylbenzene. After washing, neutralizing, drying andfractionating the reaction product, meta-l-para-diethylbenzene of purityover 99% are tained, the final output being 70% for a conversion of 33%by weight relative to ethylbenzene. In order to increase the diethylbenzene output, for the further operation together with the unreactedethylbenzene, the obtained polyethylbenzenes are also recycled. Thebenzene recovered in a pure state, due to the great difference of theboiling points, is obtained by a light rectification and can be used forother purposes.

The process according to the invention presents the followingadvantages:

The technique for obtaining diethylbenzene is simplified as the step ofobtaining ethylene is not necessary;

A more simple apparatus is required;

It allows the preparation of diethylbenzene with a final output of 70%and a conversion of 33% ethylbenzene to diethylbenzene;

The obtained diethylbenzene is a mixture of the metaand para-isomercontaining a maximum of 1.5 of the ortho-isomer.

Concerning the fact that in US. Pat. No. 2,739,993 a tremendous excessof hydrogen is required, while in the present case hydrogen is excludedfrom the reaction system it is considered that in the known processtoluene is converted into methylcyclohexane (first stage), which then,in the presence of Friedel-Crafts type catalyst, by a series ofdisproportioning and redistribution reactions of hydrogen, leads to theformation of xylenes with yields of the order of 11%. Because a complexmixture of hydrocarbons having 48% heavy hydrocarbons results from thereaction in the reference, this cannot be considered as a truedisproportionation reaction.

If the present invention were to be performed in the presence ofhydrogen, one can suppose that the use of hydrogen would decreasesubstantially the process selectivity on the basis of naphtheneformation the composition of Which would likely be similar to that givenby Ciapette (Catalysis vol. 6, Reinhold Publ. Corp. NY. 1958, p.495-687), namely:

CH3 CH 401-1 and CH3 products which appear by the opening of the ringand polymerization thereby obtaining higher parafiin hydrocarbons,probably in a higher proportion than toluene.

What is claimed is: 1. A process for preparing a mixture ofdiethylbenzenes substantially free of the o-isomer from ethylbenzene,

4 said process comprising disproportionating ethylbenzene in the absenceof hydrogen and in the presence of 3 to 10% of AlCl based onethylbenzene at a temperature of 80-100 C. to form a mixture ofdiethylbenzenes substantially free of the o-isomer.

2. A process according to claim 1 wherein 5% of AlCl is utilized.

3. A process according to claim 1 wherein the mixture is diethylbenzenescontaining a maximum of 1.5% of the o-isomer.

4. A process according to claim 1 further comprising the steps ofwashing, neutralizing, drying and fractionating the mixture.

5. A process according to claim 1 wherein the disproportionating iseffected for about 5 minutes at 100 C.

6. A process according to claim 1 wherein the mixture comprisespolyethylbenzenes and further comprising recycling the polyethylbenzenesand unreacted ethylbenzene.

References Cited UNITED STATES PATENTS 2,528,893 11/1950 Lien et a1.260672 T 2,739,993 3/1956 Schneider et a1. 260672 T 2,839,591 6/1958Enos 260672 T 2,904,604 9/1959 Couper et al 260672 T 3,306,943 2/1967Sulo et a1. 260672 T CURTIS R. DAVIS, Primary Examiner

